This is as shrewd and calculating a piece of theatrical moviemaking as you will ever see, and it is shrewd and calculating in exactly the same way that Harry Potter and the Sorcerer's Stone was. It counts not only on the moviegoer bringing with them a solid knowledge of the book, but also on the notion that most moviegoers coming to see it will be happy to watch nothing more than a two hour and forty minute transliteration of the action sequences from the book. Such assumptions as the filmmakers have made in this regard are perfectly valid, from a business point of view, but they result in a movie that cannot possibly stand on its own. In a way, Harry Potter and the Chamber of Secrets is even more calculating than the first movie, because it assumes you've seen that as well.
What they've also counted on is the fact that most people (and I certainly include myself in this group) cannot separate the book from the movie in their mind. This gives the filmmakers the freedom to excise all exposition and most character development. They know the viewer will fill in the gaps for them, so to speak, because they already know the material so well. So there's no real storytelling in the movie at all, and nothing of the filmmaker's art.
What is the filmmaker's dilemma in bringing a novel to the screen? Except in the case of very short works, it is essentially a question of what to leave out. There simply is no way to take everything from a 300-page book and fit it into a two- or three-hour movie. The best adaptations of novels tend to use the book only as a point of departure. What Columbus and company have done is to make the most economical use of the material in Chamber of Secrets. They've engineered a movie that will please the most people, by cramming in all their favorite bits from the book and thus illustrating their memories and imaginings for them.
Purely commercial movies can of course be enjoyable, as this one is, and even immensely worthwhile. The vast majority of movies that ever see the light of day are at least intended to make money, and it would be perfectly acceptable to say that in that sense all commercial films are shrewd and calculating. Does a great filmmaker like, for example, Martin Scorsese, want his pictures to do well at the box office? Of course he does. The difference between a Scorsese picture and this one, however, is that Martin Scorsese puts something of himself into his movies. They are his art form. Harry Potter and the Chamber of Secrets ought not be called a movie at all, if the movies are an art form, but rather something like a "video companion" to the book.
When I first saw Harry Potter and the Sorcerer's Stone, I had not read the book, and I came away from the movie feeling shortchanged on the story. Subsequent to that I read the book, with my daughter, bought the DVD as soon as it came out, and after several viewings over the summer grew to appreciate and enjoy the movie a great deal. It is, after all, beautifully made and loaded with wonderful and charming performances. I expect that is precisely what will happen with the second one, except that in this case, having read the book (twice), my viewing of the movie today was not disrupted by the nagging feeling that they had short-circuited the story. So this time I've got a head start when the DVD comes out.